Conventionally, there has been known a signet whose stamping face of a stamping body provided on a lower end of a signet main body and made of a porous body is caused to be in an open state when an outer frame body covering an outer periphery of a leg frame body from above is pressed and descended, the signet main body connected to the outer frame body and arranged inside the leg frame body is thereby descended, and moving in response thereto, a lid body pivotally fitted to the leg frame body is rotated. The above mentioned signet is disclosed, for example, in Japanese Utility Model Application Laid-Open Publication No. 6-67050 (Patent Literature 1). In general, this kind of a signet has a structure in which by pressing and descending the outer frame body integrated with an inner casing body holding the signet main body, the signet main body is descended inside a leg frame body and moving in response thereto, the lid body is rotated, thereby exposing the stamping face from a lower end opening of the leg frame body and allowing sealing. It is often the case that this kind of a signet is put into a pocket of clothing or a bag and carried. However, when against a user's intention, a pressing force which descends the outer frame body is exerted while such a signet is being carried in the above-mentioned manner, the signet main body is descended and the lid body with a lid in a closed state is rotated, thereby leading to a problem that the stamping face is exposed and stuff in a pocket and a bag or clothing is stained with ink.
Hence, as those which solve the above-mentioned problem, there have been stamp (or seal) holders disclosed in Japanese Patent Application Laid-Open Publication No. 10-297072 (Patent Literature 2) and Japanese Patent Application Laid-Open Publication No. 11-34462 (Patent Literature 3); and a signet (or stamp) disclosed in Japanese Patent Application Laid-Open Publication No. 2006-96003 (Patent Literature 4). Each of these stamp holders and signet disclosed therein is provided with a lock mechanism which prevents a signet main body from descending. In the stamp holder disclosed in Japanese Patent Application Laid-Open Publication No. 10-297072 (Patent Literature 2), it is required to perform locking and unlocking by means of a seesaw-type lock button. In the stamp holder disclosed in Japanese Patent Application Laid-Open Publication No. 11-34462 (Patent Literature 3), it is required to perform locking and unlocking by means of a slide button. In the signet disclosed in Japanese Patent Application Laid-Open Publication No. 2006-96003 (Patent Literature 4), it is required to perform locking and unlocking by rotating an outer frame body.
On the other hand, the automatic-inking-type rotary stamp as disclosed in Japanese Utility Model Application Laid-Open Publication No. 63-170164 (Patent Literature 5), that is, a rotary stamp whose stamping face of a stamping plate makes a half turn and advances to a position, where the stamping face is brought into contact with a target to be pressed, when a pressing force is exerted on an outer cylinder and whose stamping face thereof makes an inverse half turn and retracts so as to be brought into contact with a vermilion seal ink pad provided inside an inner cylinder when the pressing force is released is widely used for business purposes in banks, insurance companies, and the like.